Leah is a female chimpanzee, born at the Oregon Zoo on May 15, 1974, a year after Delilah's birth. She was also hand-reared and introduced into the chimp enrichment project in her first year of life, and later integrated with the older chimps.

Leah is one of Coco's daughters. She was close to her elderly mother, and was often found grooming and comforting her. After Coco's death, Leah began to follow Delilah around, looking to her older sister for security and comfort.